On Halloween 1978, Lindsey Wallace is being babysat by Annie Brackett while her parents went out for a halloween party. Throughout the night she sits and watches The Thing from Another World while Annie prepares to meet her boyfriend Paul. At first she is going to take Lindsey with her to pickup Paul but Lindsey wants to watch the movie so Annie decides to drop her off with her friend Laurie, who is babysitting Tommy Doyle at his house. Before leaving to pick up her boyfriend, Annie is killed by Michael Myers. Lindsey is then seen asleep with Tommy while Laurie goes and checks on Annie, Paul, and her friends, Lynda and Bob. Lindsey and Tommy later open the door for Laurie as she is chased back into the house by Michael Myers. After locking themselves in the bathroom and Laurie being attacked twice, Laurie tells them to go to the Mackenzies' house. Shortly after the events of that night, the Wallace family sold their home and moved to another area of town. Several years later, she is living life as a normal teenager with friends such as Rachel Carruthers, although she is in and out of therapy after what happened on that Halloween night. She also had at some point developed a drug problem, behavioural disorders and depression. She also happened to be one of the very few people other than Sam Loomis, Marion Chambers, and Tommy Doyle that knew that Laurie Strode was in hiding and was sworn to secrecy to prevent Jamie from finding out the truth that her mother was still alive and that John Tate was her brother for her own protection fearing that Michael would use Jamie to find her mother and brother.

In 2001, Michael began stalking her. He taunted the young woman by leaving a jack-o'-lantern embedded with knives in her apartment and allowing her to briefly glimpse him before he left. Now convinced that Michael is after her, she has been admitted to Smith's Grove Sanitarium. At Smith's Grove, she received psychiatric treatment from Doctor David Loomis, the son of Sam Loomis. David was fascinated by what Lindsey told him, and, despite his reservations, he began to take over his father's obsession, investigating Michael Myers' history and neglecting his other patients to spend more time with Lindsey. On Halloween, 2003, Michael returned to Smith's Grove, murdering a security guard and two nurses in his search for Lindsey. She and David tried to escape the facility, but Michael cornered them both in the lobby. As he cowered in fear under a desk, David watched as Michael sliced open Lindsey's legs and took her away. Michael left a cracked picture frame containing a photo of David and Sam in his wake, a message to David that he would be coming back for him. Lindsey's corpse was later found strung up in a pumpkin patch like a scarecrow with various knives stabbed into her torso.